[Zope-dev] Manipulating Meta-Type Global Add list on per-instance basis

[Josh Zeidner]

Hmm... possibly I did not explain my needs :

  What I need to do is manipulate the attribute of a "folderish" object ( 
ie. an object that can contain other objects ) that determines what objects 
are allowed to be contained by my object.  I need to do this at 
instantiation time , *NOT* definition time.

  I seemed to have accomplished this by manipulating the "meta_types" 
attribute...  but is this a valid way to attain this behavior?

  thanks again- Josh

>
>Josh Zeidner <jmz_phylogenic@hotmail.com> asks:
>
> >   I am currently trying to define a Z-Class that inherits from Object
> > Manager that has the special behavior of being able to change its 
>"allowable
> > sub-objects" on a per-instance basis.
> >
> > *****************
> >
> > ex.
> >
> >   I instantiate the class at a particular location I want this object to
> > only be able to contain objects of type "AppleObject" and 
>"OrangeObject".
> >
> >   I instantiate the class at another location and I want this object to 
>only
> > contain objects of type "LemonObject" and "LimeObject".
> >
> >   note that the difference here is that both of the containers are of 
>the
> > same type.
> >
> > *************
> >
> >   is it possible to have this flexibility after the ZClass has been 
>defined?
>
>If you are defining the interface (rather than accepting the default 
>"Contents"
>view), then you can do something like::
>
>  <select name="toAdd">
>    <dtml-in "filtered_meta_types( AUTHENTICATED_USER )" mapping>
>      <dtml-if "name in allowed_types">
>        <option value="&dtml-name;"> <dtml-var name>
>      </dtml-if>
>    </dtml-in>
>  </select>
>
>where 'allowed_types' is a tokens/lines property of the instance.
>
>Making this happen in the stock management interface is trickier -- you 
>need to
>overried either all_meta_types(), but finding the list of possible types, 
>so
>that the list you return contains the dictionaries required by
>filtered_meta_types().  I can't see easily off hand how to do this from 
>within a
>Python Method -- I think I would have to drop down to an External Method, 
>or
>create a new Python base class to implement this.
>
>Tres.
>--
>=========================================================
>Tres Seaver         tseaver@palladion.com    713-523-6582
>Palladion Software  http://www.palladion.com

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